Amid mixed signals on the health of the economy, average weekly mortgage rates hardly changed from the prior week.

The Freddie Mac survey showed the 30-year, fixed-rate mortgage averaged 3.98% for the week ending Thursday, barely slipping from the prior week's average of 3.99%. Last year at this time, the 30-year FRM averaged 4.87%.

The 15-year FRM, a popular refinancing choice, averaged 3.21%, down from last week when it averaged 3.23%. A year ago, the average rate for a 15-year FRM was 4.1%.

Five-year, Treasury-indexed hybrid adjustable-rate mortgages averaged 2.86%, down from 2.9% the prior week and down from 3.72% a year earlier.

And one-year, Treasury-indexed ARMs averaged 2.78%, unchanged from last week when it averaged 2.78% and down from 3.22% last year.

“The final estimate of 2011 fourth-quarter growth remained unchanged at 3%, representing the strongest pace since the second quarter of 2010,” said Frank Nothaft, Freddie Mac chief economist.

“The March 13 policy committee minutes from the Federal Reserve noted that the housing market remained depressed and supported the continuation of the maturity extension program through June 2012, but did not announce any new stimulus action beyond that date,” Nothaft said.

Home loan analytics firm Bankrate, which surveys large banks, reported the 30-year FRM rose to 4.25% from 4.23%, while the 15-year FRM fell to 3.42% from 3.44%. The 5/1 ARM inched down to 3.15% from 3.14%.